1. Field of the Invention
This invention relates to integrated vibration reducing and health and usage monitoring systems.
2. Description of the Prior Art
U.S. Pat. No. 4,819,182 discloses a vibration reducing system particularly suited for use in reducing vibration in a helicopter fuselage. To that end the prior system generates continuously a great deal of information about the structural dynamics at a range of main rotor induced harmonics, as well as information on the vibration status of the helicopter at a plurality of locations.
Health and usage monitoring (HUM) systems are being used increasingly in helicopters and as the name suggests such systems incorporate means to monitor the health and usage of both mechanical and structural components as an aid to maintenance activities and to provide warnings of impending failures which might imperil the helicopter. Additionally, vibration of a helicopter is usually monitored to provide a basis for diagnostic activity again to highlight an impending fault at an early stage.
Structural health and monitoring systems and vibration monitoring systems rely on information concerning the dynamic characteristics of the structure as well of course as the levels of vibration, and, since such information is also utilised in the aforementioned vibration reducing system, the inventor decided to investigate whether at least structural health monitoring and vibration monitoring and diagnostic systems might be integrated with vibration reducing systems thereby reducing complexity and weight.
An objective of this invention therefore is to provide such an integrated vibration reducing and health monitoring system in which various data used in the vibration reducing system are utilised also to provide a health monitoring facility.
A further objective is to provide such an integrated system which reduces vibration and provides a structural health monitoring facility and a vibration monitoring and diagnostic facility.